1. Technical Field
Example embodiments of the present invention relate to an etchant and to a method of manufacturing an array substrate using the etchant. More particularly, example embodiments of the present invention relate to an etchant etching a titanium/copper (Ti/Cu) bilayer and to a method of manufacturing an array substrate using the etchant.
2. Description of Related Art
A liquid crystal display (LCD) device may be driven by an electric circuit, for example, a thin-film transistor (TFT) circuit. Manufacturing processes for a TFT-LCD device may include a deposition process that includes depositing a metal layer using a material for source/drain electrodes, and an etching process that includes selectively removing the metal layer using a corrosive gas or a corrosive liquid to form a metal line of an electric circuit.
A plurality of thin layers or thin films may be disposed on a TFT substrate. Thus, a metal line of the TFT substrate may preferably have a gently tapered shape, of which an etching profile slopes down uniformly, and a lower width of the metal line is wider than an upper width of the metal line.
Copper may have a low resistance and may be readily and economically used. Thus, the electric resistance of a metal line formed from a copper layer may be much less than that of a metal line formed from an aluminum layer or a chromium layer. Furthermore, copper may be more environment-friendly than aluminum or chromium. However, copper may have a relatively high resistance against oxidizers compared to aluminum or chromium. Thus, an etching solution including hydrogen peroxide or ferric iron may be used for etching a copper layer.
However, hydrogen peroxide may cause disproportionation in the presence of copper ions and iron ions to be decomposed into water and oxygen. The above-mentioned disproportionation may in turn cause heat and rapid changing of compositions to thereby deteriorate manufacturing process margins and stability. To solve the above-mentioned difficulties, hydrogen peroxide may be used with a stabilizer for hydrogen peroxide, which may increase manufacturing costs.